‘Meta-analysis’ Clarifies Birth Conditions Associated with Autism

Posted by Alycia Halladay, PhD, director of research for environmental science, Autism Speaks

For over four decades, autism researchers have been combing through birth records to look for events that might increase the risk that a newborn goes on to develop an autism spectrum disorder (ASD). Many clues have emerged regarding the influence of such factors as prematurity, low birth weight, method of delivery, or even the season in which conception or delivery occurs. But no one study was large enough to provide definitive answers, and inconsistent results between studies have caused confusion among scientists as well as parents trying to follow the science.

Today, the respected journal Pediatrics publishes a study that goes far in cutting through the confusion. Researchers from Harvard and Brown universities reviewed and analyzed the combined results of 40 studies that looked at potential autism risk factors during the birth (perinatal) and newborn (neonatal) period.

Such a “meta-analysis” study is a powerful tool in science, as it allows researchers to combine and compare findings from different sources to get a clearer, more reliable picture of the associations between potential risks and conditions such as autism. Importantly, the study confirmed an association between autism and such conditions as abnormal fetal presentation during delivery (for example, breech), fetal respiratory distress (breathing difficulties), birth injury or trauma, low 5-minute APGAR score (a 1-10 score for assessing newborn health after delivery), newborn seizures, low birth weight, multiple births (twins, triplets, etc.), anemia (low blood iron, and being born in the summer.

Of note, preterm birth was not found to be associated with ASD, of particular interest because there had been considerable differences on this count across earlier studies. Most importantly, perhaps, the researchers concluded that the evidence did not implicate any one perinatal or neonatal factor as causing autism by itself. Rather, the evidence suggests that a combination of these factors—reflecting generally poor conditions during and immediately after birth–may increase the risk that a child with an underlying genetic disposition will develop autism.

One common thread across several of these risk factors is that they result in a lack of adequate blood flow to the brain during the birth process. One hypothesis is that, when combined with a genetic predisposition, oxygen deprivation to the brain worsens abnormal brain development. Studying these and other environmental (versus genetic) risk factors for autism is important to increase our understanding of the biology of ASD and to provide practical guidance for physicians and parents on how to avoid or modify those risk factors that can be changed.

In addition, this meta-analysis strongly suggests that pediatricians and parents should closely monitor the development of babies born in difficult situations so that early intervention can be offered should developmental issues such as autism arise. What this study does not say is that difficult birth means a baby will go on to develop autism. Rather, these conditions and complications may increase the risk of autism among those who have a genetic predisposition for developing it.

As in my last post, I want to invite readers to explore the many environmental risk studies that Autism Speaks is supporting with donor dollars, scientific resources, and the participation of autism families in clinical studies. Please see our Grants Search and Participate gateways at www.autismspeaks.org. Thanks for being a vital part of our mission to improve the lives of all who struggle with autism. For more on the Pediatrics meta-analysis study, also see Autism Speaks news.

Actually it used to be pacemakers and microwaves, but only if the microwave was built before 1985. Currently I know of no recommendations in regards to microwaves and heart valve replacements. Please let me know where you got your information. I’ve been a cardiac nurse for 18 years and try to keep up with the latest research.

However, I don’t think these authors gave us any new information. Yes, we all know prematurity, low birth weight, poor birthing conditions/ traumatic deliveries increase the risk of ALL developmental disorders, including autism. Agreed. But we live in the USA with the best (for better or worse) health care in the world. If challenging birth circumstances were driving autism wouldn’t we see more autism in poor communities with less access to quality healthcare? Wouldn’t we be seeing more autism among teenage Moms who often lack adequate prenatal care? Wouldn’t we be seeing more autism in rural communities or among home birth families?

If poor conditions during birth can trigger autism why are we not seeing massive amounts of autism in poor nations? Yes, these children could be excluded from society and undercounted but they would have an ASD rate 20x that of the USA. There is no hiding such a number of affected kids.

But no, it is the opposite we see the most autism among professional people with good health insurance. Yes over 40 births and multiples present higher risks but the vast majority of ASD kids are singletons, born to parents in their 20s and 30s. These parents tend to (until recently) place a great deal of trust in doctors and federal agencies and vaccinate their children right on schedule.

We cannot seriously have a conversation about environmental factors without talking about over vaccination as a trigger.

while i would like to think that vaccination was the cause of my son’s Autism I know it wasnt what triggered it and then the birthing of him he was over due and 10pd 6oz so those are ruled out too. They did mess his delievery up because he did have a low apgar score and lack of oxygen at birth. I notice things with him from birth to he was diagnosis at 18 months and we notice and questioned it all before he was a year old. I have two children and my daughter has nothing wrong with her, so until we truely find the reason for it whether through gantic testing or looking at when they were given the diagnosis we are still very blind about it all.

I agree with Katie; my son was speaking and “seemed” to be developing normally. He received his 18 months immunizations, developed a very high fever and then went silent!! No one can convince me that it was anything else! I had prenatal care all 9 months, had health insurance,middle class, college educated, delivered in one of the best hospitals in the country. My son was 8lbs-12 oz (although I had a C-section, he was breach-buttocks first). With a lot of therapy and special education and a lot of work on the part of me and my family(thanks to God and His son, Jesus Christ) my son talks, although slowly as it takes him time to process things presented to him. Vaccinations, I believe, played a major rule in his autism.

Actually, the maternal and newborn outcomes in the USA are far worse than most other industrialized nations and even most second-world areas (according to the WHO, and many other organizations). The degree of unnecessary interventions is far higher here than just about anywhere else in the world.

The quality of healthcare in the USA is better than many places, and in many areas – such as cardiac care and cancer care. However, looking at the data, it is impossible to compare quality of care for heart patients in the US to quality and outcome for mothers and babies here. Poorer mothers are more likely to enter spontaneous labor (due to less access to care) than more well-off mothers who have hyperactive-obsessive OBs who are anxious to pitocin-induce and c-section at every turn. One study I read showed that 60% of children with Autism had endured a traumatic birth that included pitocin (which increases strength and frequency of contractions, and increases the risk of hypoxia because contractions come so hard and fast that baby can’t cope well). Not a causative relationship, but certainly a risk factor for babies with a genetic predisposition to developing Autism.

Hi Katie
I agree with you. Even more, the combined effects of the tetanus shot given to pregnant women – sometimes various shots and in some countries with thimerosal and with alum- the flu shot – given at any time in pregnancy-and medications used in delivery (terbutalin) and the immunoglobulin Rh coexposure- considering the confounders such as prenatal exposure to infections and prenatal vitamins as protectors- beyond the maternal/parental age should also be considered IMO in combined impact.

Did they check the 6 month blood test for downsyndrome and other disability related bloodtests? My son had a indicator that he may have down syndrome and they wanted to do a amnio on me and I refused. I said if he had it he had it. He has been diagnosed as autistic I would like to know more about this type of research.

i had the Rh shot with both my daughter and son and i also had the h1n1 shot when i was pregnant with my son. my daughter was 4 wks early and 5 lbs 11 oz and my son was full term and 8 lbs 10oz. my daughter has autism and my son does not. withmy daughter, i do not believe that the environment and the vaccinations caused her autism, unfortunately, i believe it’s genetic with her.

Actually, the USA doens’t have the best medical practices. Europe is more advanced or maybe even Japan. The reason poor/third world countries don’t have high numbers of autism is because they don’t alter their food like industralized countries do. For instance, growth hormones used in our beef, pork, and chicken has increased…so has autism. Cows being feed corn when they’re only supposed to eat hay has increased, so has autism. The use of fertilizers and pesticides on our fruits and veggies has increased…so has autism. Third world countries don’t use or even have access to growth hormones and such. AND, hormonal birth control has increased and so has autism…..also not used in third world countries….

My daughter was an overdue (41weeks), 9lb 9oz baby, with no injury or anything else they named. she had fetal distress until they moved me to my side (resulting in my failed epidural) and she was fine. Had high APGAR at 1- and 5-minutes and was a singleton pregnancy. I wish there was a single study, just one! that would shed some light on why kids who are otherwise healthy, not a sniffle, not a fever after shots, simply don’t develop normally from birth. As an infant, my daughter had no issues, but refused to be held, hated formula warm and breast milk cold, and never made eye contact while nursing. Where’s the studies on kids like her? Or is the concern more for those kids with “regressive autism” and not “static autism”?

(Note: because of my daughter’s development and the fact that she never developed normally resulting in a diagnosis of autism, I refer to her as having “static autism” or “stable autism” as in nothing has changed, she’s always been this way. I use the term “regressive autism” to describe the children who at one point were developing normally and meeting appropriate milestones and then began to regress or stop developing normal resulting in a diagnosis of autism. I feel it is very important to distinguish the two from each other and in doing studies I feel it should be noted whether the children studied ever could have been considered to be “neurotypical”. My daughter was never considered “normal”, her behavior, from birth, has always had autistic traits.)

I agree with you. My daughter has Asperger’s while my two older boys are fine. The moment I held her in the hospital I knew something was not right. She’d scream till you put her down. As long as you left her alone she was happy. she was born full term but never hit any milestones on time. She didn’t walk completely on her own till she was over 2yrs and she never mastered crawling. Speech didn’t come till about 4yrs with therapy. She also had lots of feeding problems. She couldn’t suck a bottle and we had to drip formula from a spoon down her mouth. Swallowing was diffcult also and never could swallow baby food. She much better now with the help and schooling she’s had.

I have to agree with Katie and Maria regarding vaccines for all the reasons they stated. In my own situation, my son who was premature and did have breathing issues, also received the prescribed number of vaccines and two winters of RSV monthly vaccines. All contained thimersal. I really don’t believe I will ever be convinced that this treatment was not the catalyst for his development of autism.

I also agree with you Katie. I also think that these scientists are missing the mark though. Yes, those factors mentioned could play a role for those children who are “born” with Autism, but what about the children who “develop” Autism like my son did? I have spoken with many parents who say that they knew “something” was wrong as soon as their child was born, but on the other hand a lot of parents, such as myself, had typically developing children until AFTER the 18mo. MMR shot. My son talked, laughed, played etc… I took him in for his vaccines, wound up in the hospital that evening with him having a very high fever and covered in a rash (he was diagnosed with the measles) within a day he stopped talking, laughing, playing and did not even know who me or his father were anymore. I could say, “Ayden, give this cup to daddy” and he would look at me as if to say, what’s a cup and who is this daddy person? It broke my heart, What about those children?

My own family doctor agrees that there is a definite difference in these two types of Autism cases. He has mentioned the fact that these shots are supposed to go into the muscle, and has often wondered if this could be the result of the muscle being missed. One thing is for sure though, he agrees that NOT ALL children are “born” with Autism, that very possibly something is happening with these vaccines. Maybe they need to do a study to see what the differences are in children “born” with Autism and children that “developed” Autism, then go from there, but they just keep grouping them together when obviously two different causes are to blame.

Dawn, if I didn’t see YOUR name on here, I would swear that your story is my story….playing, laughing, talking…received 18month shots, developed a very high fever–(I commented earlier on Katie Wrights note) and then everything stopped!! There has got to be something there…and the medical community is trying to avoid the correlation or just blind to it….I don’t know…

When my child came out he had a big egg on his head….they said it was because he was in the birth canal too long, If he was in there too long then maybe he didn’t get enough oxygen.I definetly think that has something to do with his Autism. He was also placed on oxygen after he was born.

This substantiates what I’ve suspected all along. My father-in-law and my ex-husband both exhibit ASD characteristics along the lines of Asperger’s. My 16 yr old, who had the cord wrapped around his neck and had to be delivered via emergency c-section is moderate-functioning ASD. I’ve always assumed the loss of oxygen played a role in his developmental issues given his genetic predisposition. My 8 yr old son, who was delivered c-section because of his size at birth(but did not have the same oxygen deprivation) is very high-functioning ASD and an honor student.

After reading this article I am even more so confused, my son was born naturally and he was 8 lbs 4 oz far from underweight. There was no distress during pregnancy, also as it was fore mentioned earlier in comments why then hasn’t the autism rate dropped since we are in the technological age of the “highest qualified” doctors. It angers me that the thimerosal/mercury additive is still in some shots and that it seems that more excuses are being made rather than focusing on the hard facts.

While all these new findings are excellent; like previously stated we are ignoring a massive issue VACCINATIONS! Researchers seems to need to walk on egg shells to find the answers when our truth needs to be exposed for the actual facts; not just what the pharmaceutical companies and the CDC prefers!

Katie, you are right!!! Why is vaccination such a dirty word? Because it’s been “proven” to cause seizures in children under 5 and some flu shots have warned against this but nothing disclosed to the parents. What about Dr.’s advising pregnant women to get this?? How DARE they? Here go get a mercury and flu shot, by the way they change that every year, you never know what they are exposing your fetus too!!! I guess the parents 20-45% of us who BELIEVE or KNOW that these shots caused something horrible, the parents are all crazy right? NOT!!! all two hundred thousand of us who don’t know each other? or is it more like all 500,000 of us who don’t know each other. The fact that people are walking into the Dr.’s to get with a healthy infant to get shots and within 48 hours are rushing their very sick/ vomiting or high pitched crying baby/infant to the hospital should speak volumes!! IT”S Very clear to us what is causing this problem. *GREED* and NON DISCLOSURE! Mark my words, 25-50% of this can be PREVENTED. We went for generations without all this crap being INJECTED into us and there was hardly any Autism. Now, since the 1950’s and vaccination – we are seeing the Long Term Results of Screwing with our Immune Systems, Central Nervous Systems and Lungs/LIvers Organs. Chronic Illness is Up and so is Infant Mortality. PLEASE Parents – Call in those Reactions!!!! I did and guess what – that child developed AUTISM!

Thanks Alycia for the article! We have a 6yo son with Autism. We have always struggled with the idea that his congenital heart defect may have been a contributing factor to his Austism. He was found to have a heart murmur at 24 hours of life, and later found to have Tetralogy of Fallot, requiring open heart surgery at 2 months of age. Looking back at pictures of his first few minutes of life, his color was not pink, but rather a grayish tone. He also endured many “tet” spells throughout the first few months of life.
We have found that local hospitals (state of WI) are just now requiring pulse oximetry testing at birth….something that may save other children from multiple disabilities, including autism?

Is there a way I can add my son’s data to this study? I was on an SSRI at the time I unexpectedly became pregnant with my son. This was nine years ago, and at that time, no one was raising the flag about these drugs. My son was born with PPHN (Persistant Pulmonary Hypertension in the Newborn). He was in the hospital for 6 weeks after he was born (until he finally started to breathe well on his own). He was also a colicky and irritable baby. When he was three years old, he was diagnosed with PDD-NOS. I want his story to be able to help others. Thank you!

Personally, I wonder how many children, like my son who has Asperger’s, were colicky during the first 3 months of life. Was this behavior a sign of the sensory difficulties he continues to experience to this day? If it is common, it could be an early indicator that is rather easy to identify.

Also, after having my two sons, I was diagnosed with Lupus, a significant autoimmune disorder. Many others on a lupus board I frequent also have children with ASD. Coincidence?

Re: the study above, my son was born 4 days early, 7 lbs, 6 oz, no problems during pregnancy, vaginal birth following induction and use of suction and forceps due to lack of progress with pushing. However, apgar was 9 and 9 immediately after birth. After the colicky period, he seemed quite normal to me for the most part. There was no sudden regression in behavior.

Monica, I have 8 year old twins, one diagnosed with ASD. There is a genetic component with his autism and he was extremely colicky as a baby. He was in Sensory Hell until I read “The Out of Sync Child” It was almost like he was miserable until he could move around on his own. As soon as he was able to crawl he became a different baby, although very delayed by 15 months. I have Thyroid Issues, also autoimmune, and had to have surgery to remove my thyroid before undergoing fertility treatments. He has been in therapy since he was 18 months old and because of his mild condition, the school took away his IEP when he was 6, right before the law changed…I now have several diagnosis and an IEP going into 3rd grade.

I have two children with Autism. One with Aspergers and one that is more low functioning. Both children had complicated births. My son went into fetal distress and aspirated myconium. My daughter was premature, had the cord around her neck twice and her heart beat slowed tremendously during birth, then she came down with the RSV virus just a few days after birth and spent 3.5 weeks in the hospital on feeding tubes and breathing assistance. I have asked before if these birth factors could contribute to Autism and no one could answer that for me. I am so glad this study is being done.

I don’t know what caused our son’s autism (he is 49 years old), but here is how I described his birth in my diary on my blog (autism45.wordpress.com)…”Two little red pills and a “hypo” (at the doctor’s orders to help me through the pain of labor–that’s how they did it back then in 1962) soon sent me into oblivion. So much so, that I was not even aware that little Benjamin was born only two hours after I arrived at the hospital. I did not get to see him breathe his first breath, or to hold him close to me and reassure him of my love. He was on his own as he was circumcised, and was allowed to cry heartily for several hours thereafter, his arms flailing the air; shaking his fists in protest! I was told that his face and body were flushed crimson (like the cap of bright red hair he sported at birth), as he voiced his displeasure at the proceedings. He was a firecracker; both by date of birth (4th of July), and by temperament!

yep, sounds like my sons birth and my nephews birth. I had six of those markers and my sister in law had 5 of them. Combine with the predisposition (should have known my father in law! :)) and there you have it… I’ve said this for years

I appreciate the efforts of the researchers but I believe that the research community has overlooked an important factor. I would suggest that maternal exposure to medications to prevent pre-term labor be looked at as a trigger. Specifically Terbutaline and Magnesium Sulfate. I have three children, the first pregnancy I had an emergency appendectomy in month 5 and to control pre-term labor I was given oral Terbutaline for less than a month. This baby was delivered with no complications, was large for dates and had a great apgar. She is typical in every way. Fast forward a few years to 2000 and 2003 and I had rough pregnancies, brief bouts of bleeding, pre-term labor and bed rest for a month before they were delivered one month early by c-section in distress. The difference with these two is that I was on Terb from about month 5 or 6 orally, then they added the oral Mag and when that didn’t work I went into the hospital and had the max of IV Mag and Terb. Given that this happened not once but twice, in almost the same way with the end-result of children with Autism I feel very strongly that the use of these two meds was a significant factor in my children’s condition. I think parents should have access to objective data in order to make educated decisions and I urge you and those involved to do a study on these medications. If nothing else it will give those of us who have used the medications some peace of mind and if there are findings to support my assertions than warnings can be put in place to help parents make informed decisions when they are at their most vulnerable.

Have there been any long term studies regarding the liberal use of pitocin (a strong artificial hormone used to induce/augment labor and continual electronic fetal monitoring (sound waves) as it might relate to the skyrocketing autism rate. Use of Pitocin use and EFM have greatly increased in hospital births over the past 20 years.

All that and they refuse to look at children vaccinated vs those not vaccinated in the same pool of risk they evaluated. How sad that we cannot get the whole picture. I would also like to have groups look at the use of medical intervention during birth such as the use of pitocin and fetal monitoring during labor as well as those who nursed and had issues with latch due to poor muscle control.

I’d be more interested in the things they didn’t include such as Blood Type of child & mother. I once heard 70% are type A but I am not sure if this is true or not. What about a link to RhoGAM injections during pregnancy or even mercury exposure through amalgam filings. Also, what are the % of autoimmune correlations? While this study is a good start it should be expanded.

As far as the colic question. I have twin girls one with one without – The one without had colic but not the one with. Colic is a sign a dysbiosis (imbalance in intestinal flora) and is also common in food allergies and sensitivities which does seem to be more prevalent with autism.

I think one of the biggest factors in one developing autism and the other not is the level of testosterone (the girlie girl is without and the tom boy is with). The biggest factor may be the one without was a much better at excreting heavy metals. You could actually smell it in her stools following a couple of her vaccinations. At the time I had no idea they were getting exposed to metals. The heavy metal smell was so profound at her last vaccination that I thought perhaps she had swallowed coins. For several diaper changes I kept looking for the source of the metal smell.

I think it would be so helpful if we could have a platform for asking the parents what possible factors have you personally wondered about. The fact is, parents have the best ideas of what went wrong when and what contributing factors MAY have been involved. Also, exactly what % of parents like me KNOW that vaccination was mostly responsible.

Does my daughter have a genetic predisposition to environmental factors? Personally I believe so. I have had some genetic testing that have found some genetic flaws that make my detoxification system not work optimally. I suspect it is the same for her. When I can afford it I will be having her tested too. One of the flaws is in one that has already been suspected as a marker for autism. For anyone interested in the genetic testing I am talking about you can go to http://www.GeneticNutritionSolutions.com.

My son was born 3 days after I told the doctor I thought my water broke and when she did her “water test” she told me I was wrong. So when I finally went into labor and went to the hospital they yelled at me for not coming in because the was no water around the baby for 3 days. I told them what the doctor did and said and they were mad. I got to the hospital at 9am. Around 6pm his heart rate started droping they turned me on my side and started a internal bath for him. At 12:26 am he was born by emergency c-section. When he was delivered they started chest compressions right away his heart started then stoped . This went on for 3 rounds of chest compressions. Do I think this had anything to do with his Autism? You bet I do. My mother and I noticed from about 3 months old on there was something not right.

You are right, Kim. My identical twins were born 55 minutes apart and by the time the doctors pulled the second one out, by his feet, he had been without oxygen. He is on the spectrum, while his brother is not. The differences were noticeable within months.

Vaccinations have neither been proven or disproven to cause autism. It’s still a theory…I think in our case a vaccine, probably MMR, triggered autism. I am a photographer and I recently had some 5 x 7 prints made of my son before he had the MMR or last set of vaccines at age 18 months… (high pitched screaming one night). I was teary eyed in the camera store. I could not believe what a happy smiling – direct eye contact- into the camera my boy was!!! When is the CDC or better yet an independent organization going to figure this out? I thought by the time my son was 10, we would have answers…He is now 9. tick tock, tick tock.

I am glad to hear that some focus is now on the birthing process. I myself gave birth in the early 70’s with three days of labor natural child birth ido think there was a lose of oxygen in the process.

I mentioned in an earlier comment that I didn’t know what caused our son’s autism. I still don’t, but in reading these other comments, I want to say that I have wondered many times about the pitocin given in recent years too, AND the spinal-block type painkillers. Also, I checked back on our son’s immunizations, and it WAS after his eighteen months shots that he changed too! I still don’t think that has been given a fair review. I know I didn’t get to put in my two-cents worth about it! No one contacted me as a parent of an autistic child.

Sometimes the fever that follows vaccination can be a trigger for expression of an underlying genetic predisposition. This was demonstrated in a study of Australian children with a severe epilepsy syndrome called Dravet syndrome that is caused by mutation in a sodium channel gene SCN1A. For some children carrying the SCN1A mutation, their first seizure came right after vaccination and fever. But it is most likely that, even without the vaccination, the effect of the SCN1A mutation would have shown up later. I guess this is an example of interaction between genetics and environment. I agree that it is important to distinguish between stable and regressive autism in studies of environmental factors.

In regards to autism in twins: I have identical twin boys, now age 17. One is on the spectrum. Difference being, he was born 55 minutes after his brother, was born breech and blue. It is my belief that doctors should have suggested a c-section when I could not deliver him within 10 or 15 mins of his brother. He was pulled out by his feet and spent too long in the birth canal, thus losing oxygen.

In regard to Richard Knox’s “All Things Considered” (National Public Radio) report on autism in siblings (see ), all of the findings in his report (without exception) … as well as in the original “Pediatrics” article … are anticipated, reported and explained in my research on “autovirulence.” Christopher Fisher has published a succinct synopsis of these findings in:
Fisher, C. (2009). A Novel and Potentially Groundbreaking Viral Theory of Autism and Schizophrenia. Behavioral Medicine Report (Available online at ; Thursday March 19th, 2009).
Chris’ article contains a linkage to a much older unpublished version of my research.

There are three important points revealed in my research. First, autovirulence (as a phenomenon) can mimic ALL genetic findings in monozygotic and dizygotic twins. In other words, one’s pursuit of genetic explanations can lead to false premises and/or conclusions. Second, stress-activated Epstein-Barr virus and selected adenoviruses can produce the transmissible and infectious “autovirions” (i.e., small RNA secondary particles) in mothers that, in turn, lead to genetic transcription and/or translation epigenetic byproducts (“gerrs”). Those gerrs and their downstream consequences are the etiologic factors in autism spectrum disorders and associated symptoms. Gerrs also are etiologic factors in many other neuropsychiatric disorders (e.g., schizophrenia), congenital conditions (e.g., Down syndrome), most autoimmune disorders, chronic fatigue syndrome, cancers et al. Indeed, I have reported more than 120 different syndromes and conditions associated with autovirulence. Third, autovirulence teaches that stress management must receive greater attention in obstetrics/gynecology and pediatrics.

I simply can not believe the number of children being born with Autism these days. I can’t think of one of my family members or friends that aren’t effected by this disorder. The crazy thing is most people don’t know that much about it. New mothers really need to educate them selves on these birth conditions so that they know what to look for!